Which mammal cannot regulate its body temparature?

koala

sloth

elephant

bat

Unlike other mammals, sloths cannot regulate their body tem­per­a­tures, so they can only live in warm rain­forest, where tem­per­a­ture varies little in the course of the year. Sloths have very low meta­bol­ic rates and maintain low and variable body tem­per­a­tures (30–34°C or 86–93°F), reg­u­lat­ing it by moving in and out of the shade in trees.